Solutions of polyolefins and an alkoxyalkyl ester of an aliphatic monocarboxylic acid and a process for spinning same



i l l invention is as follows.

ester solvent are mixed and heated until a solution 1s United States Patent S Paul R.- Cox', Jr., and Pompelio A. Ucci, Decatur, Ala.,

assignors, by mesne assignments, to Monsanto Chemical. Company, a' corporation of Delaware No Drawing. Filed May 11, 1960, Ser. No. 28,206 19 Claims. (Cl. 260'-31;4)

This invention relates to new compositions of matter. More particularly, the invention relates to new and useful compositions of matter comprising polyolefins and a solvent therefor which are capable of being formed into useful articles such as ribbons, bristles, fibers, filaments and the like. In "addition, the present invention is concerned with a process for the coagulation of spinning solutions of polyolefins in ester solvents.

In the specification and claims herein, the term polyolefin is intended to include not only the various olefin polymers themselves, but also copolymers and terpolymers of olefins, and blends of. polyolefins with other polyolefins.

Various methods are known for converting polyolefins into fibers. and filaments, such as the melt spinning, dry spinning and'wet spinning methods.

-Inmelt spinning, the polymer in powder or pellet form is heated to a high temperature until it becomes molten and is extruded through a spinneret in the shape of filaments which harden and are set up by contact with the cooling air surroundnig the freshly extruded filaments. This method allows fairly high spinning speed, but requires oonsiderable extrusion pressure and high melt temperatures. In addition, it has been found very diflicult to melt spin polymers of high molecular weight since even at" very high temperatures the viscosity of the melt can- 'not be reduced sufficiently to permit proper extrusion through the spinneret'holes.

In dry spinning, the polymer is dissolved in a suitable solvent and the solution is extruded through a spinneret into a stream of heated gas to rapidly evaporate the solvent from the polymer and thus form the polymer filaments. This method also permits high spinning speeds but large amounts of heat-must be applied to the freshly spun filaments to remove the solvent.

I In wet spinning, a polymer solution is extruded through a spinner-ct directly into a coagulating bath; Spinning speed is slower than in the previous two methods and the composition and temperature of the coagulating bath must be carefully regulated in order to set up the freshly spun filaments and remove the proper amount of solvent fromthem.

There are a number of disadvantages to melt spinning, notably the high temperatures and pressures required, and the art has attempted to employ dry spinning and wet spinning "processes for producing polyolefin fibers, filaments and the like. Both of these latter methods employ solutions of the polyolefins. Solutions are desirable because plasticizers and other modifying agents can be more advantageously added to a solution rather than a molten composition. A lack of suit-able solvents, thosewhich are cheap and easily handled, has impeded progress in this art.

The spinning process employed in the practice of this The .polyolefin and .alkoxyalkyl formed. The solution is forced through a heated spinneret and cooled until solidification of the polymer occurs. Most of the solvent is then removed by a wash bathplaced beneath thespinneret. The fiber is immersed in. the bath a suitable length. The fiber is then airdried and stretched to maximum orientation. The drawn fibers are clear and have good tensile strength.

Patented June 11, 1963 The spinning process of this invention olfers numerous advantages over the prior art methods mentioned herein. As compared with melt spinning, the instant process may be utilized to spin olefin polymers of far greater mo lecular weight. Also bacteriostats, delustrants, pigments and other modifying agents are more easily added to a solution rather than to a molten composition. Other advantages over prior spinning processes include ease of solvent recovery and improved fiber properties. Most of the solvent is removed during fiber solidification. The remainder by washing. The fibers exhibit improved anti static properties because of residual solvent left in the fiber. Small pores left in the fiber by solvent rem-oval improve dyeability and also hand or feel. The composition of the wash bath is not critical. Solutions of water or of water plus 0.5% wetting agent, carbon tetrachloride, acetone, dimethylacetamide, i'sopropanol or other solutions which are non-solvents for the polymer, but solvents or dispersing agents for the ester solvent are effective. The distance from the spinneret to the wash bath is also not critical. Distances from 2 inches to 4 feet gave effective extraction without appreciably changing the fiber characteristics.

Accordingly, it is an object of the present invention to provide solutions of polyolefins which are capable of being transformed into shaped articles. It is also anobject of the invention to provide a process for spinning olefin polymers into filaments, fibers, rods and the like. It is another object of the invention to provide a series of novel low cost, non-toxic, high boiling solvents for polyclefins. Still another object of the invention is to provide a process for the preparation of clear viscous spinnable solutions from polyclefins and one or more of a series of novel solvents. Other objects and advantages of the instant invention will be apparent from the description thereof hereinafter.

In general, the objects of the present invention are accomplished by dissolving polyolefins in alkoxyalkyl esters of fatty acids then extruding the polymer solution through a spinneret situated a short distance above a wash bath.

The invention is practiced at an elevated temperature and pressure, depending on the nature of the solvent and the polymer and their respective concentrations in the solution. The alkoxyalkyl esters of fatty acids useful in the practice of the present invention are those having the following general formula,

wherein R is an aliphatic hydrocarbon chain containing from- 1 to 32 carbon atoms, and R is an aliphatic saturated hydrocarbon chain containing from 1 to 8 carbon atoms. As examples of such esters there may be named methoxyethyl acetate, ethoxypentyl acetate, butoxyethyl acetate, "octoxypropyl acetate, methoxyethyl propionate, ethoxypentyl propionate, butoxyethyl propionate, octoxypropyl propionate, methoxyethyl butyrate, ethoxypentyl butyrate, butoxyethyl butyrate, octoxypropyl butyrate, methoxyethyl valerate, ethoxypentyl valerate, butoxyethyl valerate, octoxypropyl valertate, methoxyethyl caprate, ethoxypentyl caprate, butoxyethyl caprate, octoxypropyl caprate, methoxyethyl laurate, ethoxypentyl lau rate, butoxyethyl laurate, octoxypropyl laurate, methoxyethyl pentadecanate, methoxyethyl stearate, butoxyethyl stearate, butoxyethyl arachate, octoxypropyl behenate, methoxyethyl oxalate, octoxypropyl oxalate, butoxyethyl rnalona-te, methoxyethyl succinate, methoxyethyl glutarate, methoxyethyl adipate, methoxyethyl sebacate, methoxyethyl acrylate, propoxyheptyl acrylate, butoxyethyl acrylate, octoxypropyl acrylate, methoxyethyl crotonate, propoxyheptyl isocrotonate, butoxyethyl crotonate, octoxypropyl crotonate, methoxyethyl isopropylacryla-te, butoxyethyl tiglate, butoxyethyl oleate, propoxyheptyl elaidate, octoxyoctyl pentatriacontenate, and the like. These esters are particularly useful in the practice of this invention because of their high boiling points, above 200 C. Other solvents for polyolefins usually boil at less than 150 C. which limits the effective spinning of polyolefins which contain more than two carbon atoms in the monomeric chain, such as polypropylene.

The olefin polymers and copolymers of this invention are those obtained by the polymerization of olefins and branched olefins containing from 2 to carbon atoms in the monomeric chain. As examples of such monomers there may be named ethylene, propylene, l-butene, isobutylene, l-pentene, 4-methylpentene-1, 2-butene, 2-pentene, Z-methylbutene-l, 2-methylbutene-2, 3-methylbutene-l, 3-ethylbutene-l, l-hexene, 2-hexene, l-heptene, 1- octene, 2-octene, 2-methylpentene-1, and the like. Also copolymers of ethylene-propylene, ethylene-isopropylene and the like.

The concentration of polyolefins that can be dissolved by the solvents of this invention depends upon the nature of the polymer, the solvent and the temperature employed. From 10 to 75 percent of polyolefin may be dissolved in the solvents of this invention when the solution is to be used as a coating, lacquer or for the production of shaped articles. When the solution is to be used in the production of fibers and filaments, it is preferred to employ from 10 to 50 percent polyolefin.

The solvents of this invention readily dissolve polyolefins within a wide range of temperature, depending upon the nature of the polyolefin, the solvent, and their respective concentrations in the solution. Although temperatures within a range of about 60 C. to 295 C. may be employed to bring about dissolution, it is preferred to employ from about 150 C. to 250 C. when the solution is to be used for the production of fibers, filaments and shaped articles.

The polyolefins of this invention may be prepared by any of several common polymerization processes well known in the art. For example, ethylene or its mixtures with other olefins can be polymerized by heating the ethylene or the ethylene mixture to a temperature of about 60250 C. in the presence of hydrides or other activators as set forth in US. Patent No. 2,699,457. In contrast, isobutylene may be polymerized at low temperatures ranging from 40 C. to 100 C. by the application of a Friedel-Crafts type catalyst, such as boron fluoride or aluminum chloride, to an olefinic mixture containing isobutylene.

The polyolefins of this invention have a wide range of molecular weight, from about 1,000 to 300,000 or greater. The preferred molecular weight range for the preparation of fibers and filaments is from about 10,000 to 50,000. Polyolefins of lower molecular weight may be used for coatings and films and higher molecular weight polyole fins may be used for molding shapes and similar articles.

The following examples are intended to illustrate the new compositions of this invention more fully but are not intended to limit the scope of the invention, for it is possible to efiect many modifications therein. In the examples, all parts and percents are by weight unless otherwise indicated.

Example I cooled and washed partially free of residual solvent by passing the threadline through an 80 C. water bath located 4 inches from the spinneret.

and exhibited good tensile strength.

The fibers were clear Example II A solution of polyethylene was formed at the same temperature and concentration as in Example I using methoxyethyl oleate as the solvent. Clear fibers with good tensile strength were obtained from this solution following the procedure outlined in Example I.

Example III A solution of polyethylene was formed at the same temperature and concentration as in Example I using butoxyethyl oleate as the solvent. The solution produced clear fibers as in Example I.

Example IV A solution of polyethylene was formed at the same temperature and concentration as in Example I using methoxyethyl stearate as the solvent. The solution produced clear fibers as in Example I.

Example V 25 grams of poly (4-methylpentene-1) and 25 grams of butoxyethyl oleate were mixed and heated, with occasional stirring, until a solution was formed at 225 C. Upon dropping the temperature to 210 C. or below the solution solidified to form a homogeneous, grainy solid. This solid was charged into an extruder equipped with a one-hole spinneret, heated to 240 C., and upon application of pressure on the extruder clear, stretchable fibers were extruded from the spinneret. A wash bath containing isopropanol was placed about 3 feet below the spinneret, so that the fiber passed through the bath which removed most of the butoxyethyl oleate solvent. Immersion length in this bath was about 4 inches. The fiber was then air dried and stretched. The drawn fiber was clear and had good tensile strength.

Example VI 5 grams of polypropylene and 45 grams of butoxyethyl laurate were mixed and heated to C. Where a solution was formed. Upon cooling to 70 C. the solution solidified. The solution was clear, viscous and produced high tensile strength fibers following the procedure outlined in Example V with the spinning temperature at 170 C.

Example VII 17.5 grams of polypropylene and 32.5 grams of methoxyethyl stearate were mixed and heated to C. where a solution was formed. The solution was viscous, slightly hazy and produced fibers following the procedure of Example V with the spinning temperature at 195 C.

As many variations of this invention may be made without departing from the spirit and scope thereof it is intended that the invention be limited solely by the scope of the appended claims.

We claim:

1. A new composition of matter comprising a solution of an olefin polymer containing from 2 to 10 carbon atoms in the monomeric chain and a solvent comprising an alkoxyalkyl ester of an aliphatic monocarboxylic acid having the general formula,

olefin polymer is polypropylene and the solvent is methoxyethyl stearate.

and 50 to 90 percent, based on the total weight of the composition, of a solvent comprising an alkoxyalkyl ester of an aliphatic monocarboxylic acid having the general fiormula,

wherein R is an alkyl radical containing vfrom 1 to 32 carbon atonrs, and R is an aliphatic saturated hydrocarbon chain containing from 1 to 8 carbon atoms.

6. The composition defined in claim 5 wherein the olefin polymer is polyethylene and the solvent is butoxyethyl laurate.

7. The composition defined in claim 5 wherein the olefin polymer is poly (4-methylpentene-l) and the solvent is butoxyethyl oleate.

8. The composition defined in claim 5 wherein the olefin polymer is polypropylene and the solvent is methoxyethyl stearate.

9. The process for preparing a new composition of matter which comprises mixing an olefin polymer containing from 2 to carbon atoms in the monomeric chain and a solvent comprising an alkoxyalkyl ester of an aliphatic monocarboxylic acid having the general formula,

wherein R is an alkyl radical containing from 1 to 32 carbon atoms, and R is an aliphatic saturated hydrocarbon chain containing from 1 to 8 carbon atoms, and heating the mixture to a temperature within a range of 150 ,C. to 250 C. until a homogeneous solution is formed.

10. The process defined in claim 9 wherein the olefin polymer is polyethylene and the solvent is butoxyethyl laurate.

11. The process defined in claim 9 wherein the olefin polymer is poly (4-methylpentene-l) and the solvent is bu-toxyethyl oleate.

12. The process defined in claim 9 wherein the olefin polymer is polypropylene and the solvent is methoxyethyl stearate.

13. A process for the preparation of shaped articles from an olefin polymer which comprises extruding a solution of an olefin polymer, containing from 2 to 10 carbon atoms in the monomeric chain, ina solvent therefor comprising an alkoxyalkyl ester of an aliphatic monocamboxylic acid having the general formula,

wherein R is an alkyl radical containing from 1 to 32 carbon atoms, and R is an aliphatic saturated hydnocarbon chain containing from 1 to 8 carbon atoms, into air to effect solvent evaporation and thereafter washing the shaped articles in a solvent removal bath.

14. The process defined in claim 13 wherein the olefin polymer is polyethylene [and the solvent is butoxyethyl laurate.

10 15 The process defined in claim 13 wherein the olefin polymer is polypropylene and the solvent is methoxyethyl stearate. I

16. The process defined in claim 13 wherein the olefin polymer is poly (4-methylpentene-1) and the solvent is 15 butoxyethyloleate.

17. A process for forming shaped articles from an olefin polymer which comprises extruding a solution containing from 10 to 50 percent by weight of an olefin polymer, containing from 2 to 10 carbon atoms in the monomeric chain, in a solvent theretor comprising an alkoxyalkyl ester of an aliphatic monocarboxylic acid having the general formula,

wherein R is an alkyl radical containing from 1 to 32 carbon atoms, and R is an aliphatic saturated hydrocarbon chain containing trom 1 to 8 carbon atoms, into air to efifect solvent evaporation and thereafter washing the shaped articles in a solvent removal bath.

18. The process defined in claim 17 wherein the olefin polymer is polyethylene and the solvent is butoxyethyl iaurate.

19. The process defined in claim 17 wherein the olefin polymer is polypropylene and the solvent is methoxyethyl 35 stearate.

References Cited in the file of this patent UNITED STATES PATENTS 2,325,963 Lott et a1. Aug. 3, 1943 FOREIGN PATENTS 575,137 Great Britain Feb. 5, 1946 614,594 Great Britain Dec. 17, 1948 OTHER REFERENCES Noller: Textbook of Organic Chemistry, Saunders Co., New York 1951, page 523. 

1. A NEW COMPOSITION OF MATTER COMPRISING A SOLUTION OF AN OLEFIN POLYMER CONTAINING FROM 2 TO 10 CARBON ATOMS IN THE MONOMERIC CHAIN AND A SOLVENT COMPRISING AN ALKOXYALKYL ESTER OF AN ALIPHATIC MONOCARBOXYLIC ACID HAVING THE GENERAL FORMULA
 2. THE COMPOSITION DEFINED IN CLAIM 1 WHEREIN THE OLEFIN POLYMER IS POLYETHYLENE AND THE SOLVENT IS BUTOXYETHYL LAURATE.
 3. THE COMPOSITION DEFINED IN CLAIM 1 WHEREIN THE OLEFIN POLYMER IS POLY (4-METHYLPENTENE-1) AND THE SOLVENT IS BUTOXYETHYL OLEATE.
 4. THE COMPOSITION DEFINED IN CLAIM 1 WHEREIN THE OLEFIN POLYMER IS POLYPROPYLENE AND THE SOLVENT IS METHOXYETHYL STEARATE. 